Technological aid for transfemoral amputees

ABSTRACT

An aid device for the motor disabled, suitable for allowing walking of transfemoral amputees, having: a lower-limb prosthesis of an amputated limb; a lower-limb orthosis suitable to be worn at a sound contralateral lower-limb; an orthotic pelvis module connecting the prosthesis to the lower-limb orthosis; and a control unit for the operational coordination of movements of the prosthesis and the lower-limb orthosis.

FIELD OF THE INVENTION

The present invention relates to an aid device for the motor disabled,particularly suitable for lower leg amputees.

The work leading to this invention has received funding from theEuropean Union Seventh Framework Programme FP7/2007-2013, within theframework of the CYBERLEGs Project, grant agreement n° 287894.

BACKGROUND OF THE INVENTION

Lower-limb loss is a potentially disabling condition affecting thehealth and well-being of persons worldwide.

Across the globe, lower-limb loss has been acknowledged as a significantpublic health issue, and strategies have been developed to reduce theburden of disease (Ephraim, Dillingham, Sector, Pezzin & MacKenzie,2003). To better quantify the incidence of lower-limb amputations andhave a dimension of the problem, we should realize that every year—onlyin US—about 150,000 people undertake a lower-limb amputation caused by avascular disease (http://www.amputee-coalition.org).

There are multiple pathways to the loss of a limb, including diabetesmellitus, peripheral vascular disease, trauma, malignancy, andcongenital limb deficiency. Universal to all developed countries thereare two main factors influencing the amount of lower-limb amputations.The first factor is peripheral vascular disease, which is in most of thecases caused by diabetes mellitus (amputations caused by a vasculardisease are called dysvascular). It is estimated that, in US, 80% of alllower-limb amputations are dysvascular, while those caused by trauma areabout 15% (other causes are cancer or congenital diseases). The secondfactor is the age-related increase of low-extremity amputationssecondary to peripheral vascular disease, with over-70 people being theones having the highest risk of undertaking dysvascular amputation(Dillingham, Pezzin, & MacKenzie, 2002; Ephraim et al., 2003; The GlobalLower Extremity Amputation Study Group, 2000). This latter aspect is acritical point if we consider that ageing is one of the future socialchallenges for Europe. In fact, in 40 years from now, nearly 35% of thepopulation of Europe is projected to be 60 years of age or over and weshould consider now how to evolve towards a society where this part ofthe population will remain creative, productive, autonomous, andindependent.

Lower-limb amputation can be performed at several levels (e.g.foot-level, calf-level, thigh-level). Although all amputations lead to adisabling condition for the patient, thigh-level amputations (namelytransfemoral) are clearly the most challenging amputation level for theamputee, the surgeon, prosthetists, therapists, and every member of thehealthcare staff. Transfemoral amputees are estimated to be about the20% of the total lower-limb amputations, this means about 30,000 peryear, only in US (Dillingham et al., 2002). In Europe data are verysimilar.

Drawbacks Associated with the use of Prior Art Prostheses

Transfemoral amputation is a big challenge for the amputee's daily life.

In fact, persons living with transfemoral limb loss face multipledistinct challenges, namely: (i) they need more metabolic energy andcognitive effort to perform any locomotion-related task (e.g. gait,climbing stairs), (ii) their locomotion is less stable, (iii) they needa more complicated prosthetic device, (iv) they face a tremendousdifficulty rising from a seated position, and (v) differently fromamputees with amputations at the tibia and the foot, they lackprosthetic comfort while sitting.

Generally speaking, transfemoral amputees using a prosthesis arerequired more energy to walk, at the same time achieving lower speedsthan non-amputees.

No lower-limb amputation is “easy” to adapt to, but the transfemoralcertainly offers more challenges than amputations in the calf or foot.Studies show that the higher the amputation level, the more energy isneeded for walking. A famous study of Waters et al. (1976) looked atgait and energy use among 70 people with lower-limb amputations atseveral levels. In this study it was shown that transfemoral amputeeschoose the slowest gait speed (about 60% of the one of non-amputees),and consume 1.3 times the energy that non-amputees consume for walkingthe same distance. These values become even worse in the case ofdysvascular amputees: about 40% of the non-amputee gait speed and 2.5times the energy that non-amputee expend. In other terms, a person witha dysvascular transfemoral amputation usually walks more slowly thanbefore but expends much more energy because it takes a greater effort towalk after amputation.

Steps, Stairs and other ups & downs are particularly challenging tasks.

People with transfemoral limb loss do not go “step over step” as theywalk up or down stairs. Rather, they tend to go “step by step”, onestair at a time. Typically, an individual with transfemoral limb losswill first step up with the sound leg (i.e. the contralateral leg), thenbring the prosthetic side up to the same step. In this case thecontralateral sound leg become fundamental to accomplish the desiredmotion task. This is because the passive prosthetic knee does notprovide the power necessary to take the person up to the next higherstep. Loss of knee and ankle torque is one of the factors that rises thechallenge to adjust to a new way of walking after a transfemoralamputation.

In general terms, more “mental energy” is requested to the amputees,although less gait stability is achieved.

Transfemoral amputees face more problems with stumbling and falling, andmuch greater concentration is needed for walking. While traditionalresearch such as the aforementioned Waters' work looked at the physicalenergy required for walking, newer research is trying to measure themental energy involved (Datta & Howitt, 2005), namely:

-   -   “the conscious effort of thinking about walking and moving with        the prosthesis”;    -   “the stumbling”, which is a “near miss” and does not        systematically imply a fall; it corresponds to a stop or a        change in the rhythm of the walk: recovery from stumble often        requires a “stutter step”, a hop or a shift in weight balance;    -   “the semi controlled fall”, which occurs when the amputee        recognizes the incipient fall, and as it occurs he/she grab onto        something to either break the fall or land in a controlled        manner;    -   and finally, the “uncontrolled fall”, which is very risky for        amputee health (http://www.amputee-coalition.org).

While stumbling and falling are clearly issues for all lower-limbamputees, the higher the amputation level, the greater the risks offalling. Walking is automatic for most individuals, with almost noconscious thought. A person with a transfemoral amputation, on the otherhand, must really focus on walking, especially on uneven surfaces,stairs and inclines, and in unfamiliar areas. Different environments canbring different and sometimes hazardous challenges. It's one thing totake a leisurely walk on an even, smooth pathway, but it's somethingelse altogether to navigate an area such as an airport concourse wherepeople are walking at many speeds, stopping and starting, and coming inand out of “your space” from all directions. It is in this case that theamputee has to make countless gait.

As a consequence of all said challenges, energetic, cognitive andstability difficulties are not fully overcome by any artificial passiveor active transfemoral prosthesis in the current state of the art. Theconsequence is that most of dysvascular transfemoral amputees (who arethe more affected by these issues) do not use any prosthesis.

A few amputees (about 20%) use the prosthesis to walk or move. Ratherthey use alternative biomedical means such as wheelchairs. In many casesthe medical doctors prohibit the use of the prosthesis because thereduced energy-efficiency of the resulting gait would be not sustainableby the weak cardiovascular system of the dysvascular amputee. Indeed,the presence of the passive prosthesis yields to a demanding additionalload on the contralateral limb, which is often also impaired andaffected by the same peripheral vascular disease.

The prosthesis requires the amputee to re-learn how to walk, by adaptinghis/her physiological gait pattern to the capabilities of theprosthesis. Some of these issues have been tackled by state-of-the-artsemi-active or active prostheses. The first are like conventionalpassive prostheses, augmented with an active knee brake, the latterbeing real active devices that can provide positive power to the gait,reducing the burden on the user, and ensuring a more “physiological”pattern. Unfortunately, both active and semi-active prostheses aremostly used by young, healthy trauma amputees, while are still unusablefor dysvascular amputees. Indeed, they unacceptably load thecontralateral limb and are then extremely energy-inefficient for theamputee.

U.S. Pat. No. 3,995,324 discloses a passive device for moving theartificial leg of an amputee. The device includes a first articulatedhip joint assembly carried at the natural leg and a second articulatedhip joint assembly carried by the prosthesis. Energy from the movementof the natural leg is transferred to the movement of the artificial leg.

SUMMARY OF THE INVENTION

The technical problem underlying the present invention is therefore toovercome the drawbacks mentioned above with reference to the state ofthe art.

The above problem is solved by an aid device according to claim 1 and bya method according to claim 23.

In particular, in its most general definition the invention provides anaid device comprising a prosthesis of an amputated limb and an orthosis,the latter suitable to be worn at another body portion and preferablypowered/motorized. The prosthesis and the orthosis are operativelyconnected and jointly controlled. Preferably, the orthosis comprises afirst limb module to be worn at a (sound) limb contralateral to theamputated one and a second connection module for connecting the firstmodule to the prosthesis.

For “operatively connected” it is meant that the prosthesis and theorthosis can be mechanically/structurally connected one to the otherand/or functionally connected, in this latter case being controlled,typically electronically, by a common control unit.

The proposed combination of a prosthesis with an orthosis can be named“ortho-prosthesis”. Such ortho-prosthesis is conceived as a complex“wearable” robotic device which acts and cooperates closely to a humanbeing.

Further preferred features of the invention are indicated in thedependent claims.

In particular, in a preferred embodiment the prosthesis is a lower-limbprosthesis and the orthosis comprises a first module being a lower-limborthosis and a second module being a pelvis module connecting thelower-limb prosthesis and the lower-limb orthosis.

Similarly, according to another preferred embodiment the prosthesis andthe first orthosis module are wearable at an amputated upper limb and ata contralateral (sound) upper limb, respectively, and the secondorthosis module is apt to be worn at the back of the subject.

The aid device according to the invention implements a novel concept ofa technological biomedical aid which allows amputees, particularlytransfemoral amputees, to lower the energetic and cognitive loadnecessary to walk and/or to perform other locomotion-related tasks, suchas “climbing stairs”, standing up, and so on.

The aid device according to the invention increases amputee's efficiencyboth under a metabolic and cognitive point of view, thanks to thecombination of a prosthesis with an orthosis and to the operativeconnection between them and to their joint control. In particular, suchconnection and control, through passive or active (i.e. powering)components can allow a load transfer between the prosthesis and theorthosis and/or a coordinated movement of the two.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, reference will be made to the figures of the annexeddrawings, wherein:

FIG. 1 shows a schematic perspective representation of an aid deviceaccording to a preferred embodiment of the invention;

FIG. 2 shows a diagram illustrating the operation modes of a controlunit of the device of FIG. 1;

FIGS. 3A and 3B show a front and posterior view, respectively, of aspecific implementation of the aid device of FIG. 1, wherein only asub-group of the hardware components of this figure have beenrepresented; and

FIGS. 4A and 4B show a front and posterior view, respectively, of an aiddevice according to another preferred embodiment of the invention,wherein there have been represented the main hardware components.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

With reference initially to FIG. 1, it is shown an aid device 1 for themotor disabled according to a preferred embodiment of the inventionwhich applies to transfemoral amputees.

Device 1 is conceived as an artificial cognitive system for thelower-limb functional replacement and assistance in daily livingactivities in transfemoral amputees.

Device 1 comprises a lower-limb prosthesis 2 for the amputated limb andan orthosis 3, the latter comprising a limb orthotic module 31 apt to beworn at the contralateral (sound) lower-limb and a pelvis module 32.Pelvis module 32 mechanically connects prosthesis 2 and limb orthoticmodule 31.

In the present example, both prosthesis 2 and limb orthotic module 31have respective flexion/extension degrees of freedom at an ankle and ata knee portion thereof. The elements allowing such degrees of freedomare represented schematically in FIG. 1 and denoted by 51 and 52 forprosthesis's knee and ankle, respectively, and by 53 and 54 for knee andankle of limb orthotic module 31, respectively. Preferably, the degreesof freedom of prosthesis 2 and of limb orthotic module 31 are active,i.e. powered, as explained in greater detail later on.

Moreover, also pelvis module 32 has at least one degree of freedom, inthe present embodiment three degrees of freedom at each hip portion, inparticular hip flexion/extension, hip intra-extra rotation and hipabduction/adduction. The elements allowing such degrees of freedom arerepresented schematically in FIG. 1 and denoted globally by 55. Thedegrees of freedom of pelvis module 32 allow the amputee to freely movehis/her hips in space according to physiological movements. In thepresent embodiment, the degrees of freedom of the pelvis module in hipintra-extra rotation and hip abduction/adduction are passive, i.e. notpowered, whereas hip flexion/extension is active, i.e. powered.

Prosthesis 2 and orthosis 3 represent mechatronic sub-systems of device1.

Advantageously, device 1 also comprises passive components, preferablyelastic components, allowing at least a partial load transfer fromprosthesis 2 to limb orthotic module 31 and/or vice-versa during theexecution of a motor task. Preferably, such passive components arearranged at pelvis module 32, in particular endowed in hip intra-extrarotation and abduction-adduction joints.

In the present example, when prosthetic leg 2 is in the stance phase,the weight of limb orthotic module 31 is partially unloaded onto ground,through pelvis module 32, by a foot 21 of prosthesis 2, and vice versawhen the limb orthotic module 31 is in the stance phase. Limb orthoticmodule 31 touches the ground through a flexible plate-like mechanism 310parallel to the amputee's foot.

Device 1 also comprises means for supplying external energy toprosthesis 2 and to limb orthosis 31. In a variant embodiment, pelvismodule 32 can be energized as well, in combination or in alternativewith energization of limb module 31 and/or of prosthesis 2.

In the present example, device 1 includes an on-board energizing unit 6arranged at pelvis module 32, as shown schematically in FIG. 1. Asmentioned above, in the present embodiment energizing unit 6 is apt toprovide full or auxiliary power at the aforementioned degrees of freedomof prosthesis 2 and limb orthotic module 31. Energizing unit 6 may beimplemented by a battery pack.

Device 1 also comprises a sensory system, preferably comprisingmulti-modal sensors. Preferably, such sensory system allows monitoringone or more of the following:

-   -   prosthesis and/or orthosis status—in particular, active and        passive joints are equipped with position and torque sensors;    -   amputee's body motion and/or status—in particular, inertial        measurement units (IMUs) are placed on the upper part of the        patient body, preferably at pelvis module 32, to monitor torso        and upper-limb posture/orientation, angular velocities and        accelerations;    -   interaction between subject and device 1—in this respect,        orthosis 3 may have shells covered with distributed pressure        sensors, which provide an estimate of the patient-device        interaction force;    -   interaction between prosthesis 2 and/or limb orthotic module 31        with the ground—in this respect, prosthesis foot 21 and        amputee's foot are equipped with a respective sensorized foot        insole, which preferably provides an estimate of the vertical        ground reaction and the coordinates (on the foot surface) of the        centre of pressure (CoP).

Generally speaking, the sensory system may comprise sensors formonitoring one or more of the following: linear and/or angular positionof part(s) of device 1 and/or of the subject; forces and/or pressureand/or moments at part(s) of device 1, at the ground and/or betweensubject and device 1; speed and/or acceleration of part(s) of device 1and/or of the subject.

Preferably, the sensory system is distributed over device 1 andcomprises wireless sensors. By way of example, a few sensors are shownin FIGS. 1 and 2 and one of them is denoted by 7.

Device 1 also comprises a control unit 8 in communication withprosthesis 2, orthosis 3, energizing unit 6 and the sensory system.Preferably, communication between control unit 8 and the aforementionedsensors and/or the other components of device 1 is obtained by awireless network.

Control unit 8 is shown also in FIG. 2 and denoted as “cognitive controlunit”.

Preferably, also control unit 8, or at least computational meansthereof, is arranged at pelvis module 32, as shown schematically in FIG.1.

Operation modes of control unit 8 and the associated data flow with theother components of device 1 are shown, by way of example, in FIG. 2. Asshown in said Figure, device 1 closes the loop with the amputee by meansof an efferent feedback unit 81, preferably comprising vibro-tactilemodules embedded in the human-robot physical interfaces. The latterprovide the amputee with a feedback on robot, user-robot interaction andground interaction status. In the example of FIG. 1, one of suchvibro-tactile units is shown arranged at the prosthesis stump anddenoted by 9. Control unit 8 processes all data from the device sensorysystem and preferably give as output an estimation of one or more of thefollowing:

-   -   a) the “amputee motor intention”, which means to identify which        locomotion-related task (e.g. walking, stairs climbing), or        which motor transient (e.g. start and stop walking,        sit-to-stand, or stand-to-sit) the amputee wants to perform, as        well as close-to-real-time high level parameters characterizing        this intention (e.g. gait cadence, etc.);    -   b) a “prevision of the risk of fall”, which means that the        fusion algorithm will be able to timely address questions such        as: “Is the subject close to fall down?”, “Is the subject        stumbling?”;    -   c) an “evaluation of the amputee psychophysiological stress        level”, which means that the control system can evaluate the        level of effort of the user to accomplish a certain motor task;        we should imagine this output as an index which correlates to        the amputee (physical and mental) effort;    -   d) the identification of the current “device-amputee system        status”: control unit 8 recognizes specific states like gait        states (e.g. hell strike or toe-off) or posture states (e.g.        weight transfer from prosthesis to orthosis).

Outputs a) to c) enter as inputs in a motor-primitive based controlsystem of prosthesis and orthosis. More specifically, the “amputee motorintention” is used to select which motor primitive will be run forcontrolling the prosthesis, orthosis and their dynamical coupling. The“prevision of the risk of fall” is used for fast modification of motorprimitive parameters to initiate counter-measures to the detected fall.Finally, “the evaluation of the amputee psychophysiological stresslevel” is used to change motor-primitives parameters to provide theamputee with higher motion assistance and smoothly bring the amputee ona less-tiring steady-state condition. Being the selected motor primitiverunning, prosthesis and orthosis joints are preferably driven through animpedance control strategy. For the orthosis an alternative‘zero-impedance joint torque control’ strategy is available. This modeis used to provide assistive torque with minimum output impedance, whenneeded. Last, but not least, output d) of the multi-sensory fusionalgorithm, the “amputee-device system status”, enters the efferentfeedback unit block. In the present embodiment, as said above the statusis encoded in a vibro-tactile temporally-discrete stimulation of afunctional site of the amputee (e.g. the amputee's stump).

Therefore, control unit 8 of aid device 1 is based upon motor primitivesas fundamental buildings block, thus endowing the device withsemiautonomous behaviour for planning the motion of the prosthesisjoints and the assistive action of the orthosis module. The device iscapable of high-level cognitive skills, interfaced to the amputeethrough a bi-directional interaction.

Moreover, control unit 8 evaluate possible amputee's psychophysiologicalstress condition and on-line adapt the assistance strategy, as well asthe gait pattern. Control unit 8 also provides the user with anaugmented efferent feedback on the amputee-device status, thus promotingthe emergence of a sense of body-ownership (cognitive efficiency).

Some of the components introduced so far are shown in further detail inFIGS. 3A and 3B.

The specific implementation of device 1 shown in FIGS. 3A and 3Bcomprises prosthesis 2 with two active degrees of freedom, pelvis module32 with two active degrees of freedom for the assistance offlexion-extension at each hip, and limb orthotic module 31—namely aknee-ankle-foot orthosis—with two active degrees of freedom forassisting flexion-extension of the knee and ankle joints of the soundlimb.

Prosthesis 2 is connected to pelvis module 32 by means of a passivemechanical coupling which will be detailed later on.

Prosthesis 2 is also connected to a thigh socket 20 by a standard tube200 for prosthetics application.

Pelvis module 32 comprises a C-shaped frame 320 which houses—for eachhip joint—a rotational actuator, in particular a motor, for assistingthe hip flexion-extension. These two actuators are schematicallyrepresented in FIG. 3A and 3B and denoted with 555 and 556,respectively.

As mentioned above, pelvis module 32 is also endowed with two passivedegrees of freedom for each hip joint, namely intra-extra rotation andabduction-adduction. C-shaped frame 320 of pelvis module 32 also housestwo passive joints for intra-extra rotation and abduction-adduction.

C-shaped frame 320 is also connected to tailored pelvis orthotic shells325, fastened together by belts 326. Shells 325 and belts 326 allow themechanical coupling of frame 320, and generally speaking of pelvismodule 32, with the user pelvis.

For the amputated limb, hip flexion-extension actuator 555 transfers theassistive torque to the stump by means of a rigid bar 50 connected toprosthesis 2 by means of the aforementioned passive mechanical coupling.For the sound limb, hip flexion-extension actuator 556 transfers theassistive torque to the thigh by means of a rigid bar 57 connected to anorthotic cuff 550. Bar 57, which is parallel to the thigh of the soundlimb, is then connected to knee-ankle-foot orthosis 31.

Knee-ankle-foot orthosis 31 comprises two rotational actuationunits—denoted by 53 and 54 for consistency with FIG. 1—for theassistance of knee and ankle flexion-extension, respectively. These tworotational actuation units 53 and 54—based upon rotational motors—arecoupled by a rigid bar link 58 that interfaces the shank of the soundlimb by means of a further orthotic cuff 551. Finally, the ankle motorof unit 54 moves a rigid link which is mechanically coupled to the shoeof the sound limb and which is denoted with 310 for consistency withFIG. 1.

In the example of FIGS. 3A and 3B, battery pack 6 and control unit 8 ofdevice 1 are housed within a back pack 60 which is worn by the user bymeans of belts.

The weight of device 1 is partially transferred to the amputee's back bymeans of belts 328.

Finally, other belts 327, passing under the groin, avoid the systemslipping upwards as a consequence of the interaction of device 1 withthe terrain.

Of course, variant embodiments may provide different means for said leadtransfer to the back and/or for avoiding said slipping.

FIGS. 4A and 4B relate to a different embodiment of the device accordingto the invention, globally denoted by 10, wherein a thigh orthosismodule 311 only is provided, i.e. the orthotic module does not extend tothe knee and shank.

The remaining components, degrees of freedom and operation modes ofdevice 10 can be the same as already described in conjunction with FIGS.1 to 3B.

It will be appreciated that the aid device described above provides amulti-degree-of-freedom system with both lower-limb replacing andassistive capacities and allows the user to use the robotic aid on awhole-day basis.

It will be now better understood that the aid device of the invention,particularly in the embodiments described above, improves the amputee'sefficiency under both a metabolic and a cognitive point of view.

As far as metabolic efficiency is concerned, the device allowsdecreasing the cardiovascular and muscular load on the amputee, to allowhim/her to use the robotic aid on a whole-day basis. This is achievedthrough the presence of both the active transfemoral prosthesis, whichpursues the functional replacement of the propulsion function of theamputated limb through active knee and ankle joints, and thepower-augmentation wearable orthotic device on the contralateral limb,which supports the “weak” sound leg in the hard task to compensate theefficiency deficit introduced by the active prosthesis.

As far as cognitive efficiency is concerned, thanks to the control unitand the feedback efferent unit, the device ensures the lowest cognitiveload for the amputee. This is reached primarily by sharing the cognitiveeffort for the control between the user and the robot. The devicebehaves largely as a semi-autonomous, intelligent and bio-inspired pairof robotic legs, i.e. the prosthetic and the orthotic legs. Theprosthetic leg functionally replaces the biological amputated leg. Theorthotic device acts in parallel to the sound leg of the amputee. Inboth cases, a bio-inspired control approach based on motor primitivesensures the prosthetic leg to behave like a normal leg and the orthoticdevice to naturally co-operate with the sound limb, with very littleneed of conscious control from the user.

In particular, the device is able to infer the amputee's motorintention—and then to use it to control both prosthesis and orthosis—byprocessing the information coming from the human-robot interface. Suchhuman-robot interface (connecting the movement intentions of the amputeewith the actual motion of the robotic modules) relies on a completemonitoring of the movement of the user himself obtained through apervasive, miniaturized, distributed sensing apparatus to monitor allthe relevant kinematical and dynamical data from: the robot itself, theuser's contralateral limb, hips and upper body; the device and amputeefeet interaction with the ground; and the interaction forces at thephysical interface between the amputee and the orthotic device. Themotor intentions of the user are deduced—and then used to control therobot—from the movement of the rest of the body, therefore requiring theamputee to give little to none conscious effort to control the deviceand cooperate with it. The detected high-level motion intention is usedto control the global functional task of the device (e.g. move forward,move backwards, stop, climb a stair step). Aside this command, theprosthesis behaves autonomously regarding the control of the singleactuated joints.

By processing the information coming from the human-robot interface, thedevice is able to detect when the amputee is stumbling or is close tofall down. Having detected this risk, the device control system can helpthe amputee to execute the appropriate recovery action. Thanks to thisskill, transfemoral amputees who will use the device are not frustratedby continuously thinking about walking and moving with the prosthesis.

By monitoring some physiological parameters, such as skin temperature,conductance and hearth-rate, the device is able to evaluate possibleamputee psychophysiological stress condition. The idea is that if thedevice realizes that the amputee is under (physical or mental) stress,it can act on the control strategies by changing the type of assistance(e.g. increasing the amount of torque assistance) or the gait parameters(e.g. by reducing the gait cadence). Finally, the device is able toprovide the user with an augmented efferent feedback on theamputee-device status. Providing the amputee with a feedback on systemstatus contributes to perceive the device as a part of his/her own body,i.e. to promote the sense of body-ownership. The efferent feedbackcontributes to reduce the amputee cognitive effort. Indeed, receiving afeedback from the technological aid on system status helps the amputeeto increase his/her confidence in the device support, thus reducinghis/her mental effort.

The invention provides also a method of allowing the execution of amotor task by a motor disabled, which method comprises the step ofproviding an aid device as described above.

The present invention has been described so far with reference topreferred embodiments. It is intended that there may be otherembodiments which refer to the same inventive concept, that may fallwithin the scope of the appended claims.

BIBLIOGRAPHY

-   -   Datta D., Heller B., Howitt J. (2005). A comparative evaluation        of oxygen consumption and gait pattern in amputees using        Intelligent Prostheses and conventionally damped knee        swing-phase control. Clin Rehabil, 19:398-403.    -   Dillingham T. R., Pezzin L. E., MacKenzie E. J. (2002). Limb        amputation and limb deficiency: epidemiology and recent trends        in the United States. South Med J., 95(8):875-883.    -   Ephraim P. L., Dillingham T. R., Sector M., Pezzin L. E.,        MacKenzie E. J. (2003). Epidemiology of limb loss and congenital        limb deficiency: A review of the literature. Archives of        Physical Medicine and Rehabilitation, 84(5): 747-761    -   The Global Lower Extremity Amputation Study Group (2000).        Epidemiology of lower extremity amputation in centres in Europe,        North America and East Asia. British Journal of Surgery,        87:328-337.    -   Waters R. L., Perry J., Antonelli D., H. Hislop (1976). Energy        cost of walking of amputees: the influence of level of        amputation. The Journal of Bone and Joint Surgery, 58(1):42-46.

1. An aid device for the motor disabled, particularly suitable forallowing walking of transfemoral amputees, comprising: a prosthesis ofan amputated limb; an orthosis suitable to be worn at another bodyportion, wherein said prosthesis and said orthosis are operativelyconnected one to the other, a control unit in communication with bothsaid prosthesis and said orthosis, and a sensory system in communicationwith said control unit.
 2. The device according to claim 1, wherein saidorthosis is configured to be worn at a limb contralateral to theamputated limb.
 3. The device according to claim 2, wherein saidprosthesis is a lower-limb prosthesis and said orthosis comprises alower-limb orthosis, the lower-limb orthosis extending at a sound limbthigh and preferably also at a sound limb shank.
 4. The device accordingto claim 2, wherein said prosthesis and/or said orthosis have at leastone flexion/extension degree of freedom, preferably twoflexion/extension degrees of freedom.
 5. The device according to claim1, wherein said prosthesis is a lower-limb prosthesis and has a degreeof freedom at an ankle and/or at a knee portion.
 6. The device accordingto claim 1, wherein said orthosis comprises a lower-limb orthosis andhas a degree of freedom at an ankle and/or at a knee portion.
 7. Thedevice according to claim 1, comprising means for supplying externalenergy to said prosthesis and/or to said orthosis.
 8. The deviceaccording to claim 7, wherein said means for supplying external energycomprises an on-board energizing unit.
 9. The device according to claim1, wherein said orthosis comprises a first limb orthotic moduleconfigured to be worn at a limb contralateral to the amputated limb anda second connection orthotic module mechanically connecting said firstorthotic module to said prosthesis.
 10. The device according to claim 8,wherein said orthosis comprises a first limb orthotic module configuredto be worn at a limb contralateral to the amputated limb and a secondconnection orthotic module mechanically connecting said first orthoticmodule to said prosthesis, and wherein said energizing unit is arrangedat said second orthotic module.
 11. The device according to claim 9,wherein said second orthotic module has at least one degree of freedom.12. The device according claim 9, wherein said second orthotic module isconfigured to be arranged at the pelvis or back of an amputee andpreferably has at least one degree of freedom at each hip, mostpreferably three degrees of freedom at each hip.
 13. The deviceaccording claim 12, wherein said second orthotic module has at least oneflexion-extension degree of freedom, preferably a powered degree offreedom, at each hip.
 14. The device according to claim 9, comprisingpassive components, preferably elastic components, allowing a loadtransfer from said prosthesis to said orthosis and/or vice-versa duringthe execution of a motor task, wherein passive components are preferablyarranged at said second orthotic module.
 15. The device according toclaim 9, wherein said control unit is arranged at least partially atsaid second orthotic module.
 16. The device according to claim 9,wherein said control unit comprises means for estimating one or more of:a subject's motor intention concerning the specific motor task to beperformed; a risk of fall; a subject's psycho-physiological stresslevel; motor primitives to be followed by said prosthesis and/or saidorthosis.
 17. The device according to claim 16, wherein said controlunit is suitable to output efferent feedback data to the subject wearingthe device.
 18. The device according to claim 17, comprising avibro-tactile unit to provide said feedback.
 19. The device according toclaim 17, wherein said control unit is suitable to implement animpedance control strategy.
 20. (canceled)
 21. The device according toclaim 1, wherein said sensory system comprises sensors for monitoringone or more of the following: prosthesis and/or orthosis status;subject's body motion and/or status; interaction between subject andprosthesis and/or orthosis; interaction between said prosthesis and/orsaid orthosis with the ground.
 22. The device according to claim 1,wherein said sensory system comprises sensors for monitoring one or moreof the following: linear and/or angular position of part(s) of thedevice and/or of the subject; forces and/or pressure and/or moments atpart(s) of the device, at the ground and/or between subject and device;speed and/or acceleration of part(s) of the device and/or of thesubject.
 23. (canceled)